Optical waveguides have a physical structure that guides electromagnetic waves in the optical spectrum (e.g., light). In some cases, an optical waveguide can be an optical fiber or a planar waveguide structure. An optical waveguide can use total internal reflection (TIR) to guide light to an output. Depending on an incidence angle of light with respect to surface normal of a TIR surface, the intensity or power distribution of the light may vary. Thus, an area of an optical waveguide may receive more or less energy from the light being guided due to the incidence angle of the light. In some cases, this spatially-inhomogeneous power distribution is irrelevant to the operation of the optical waveguide. In other cases, however, inhomogeneity of light propagated through a waveguide can result in performance deficits for certain TIR device applications. Accordingly, it may be beneficial to homogenize the power distribution of light for a particular area of an optical waveguide or TIR device.
A TIR imaging device may suffer performance deficits due to mode inhomogeneity of light propagated through a waveguide. For example, light may enter a waveguide, propagate through the waveguide, and reflect towards an exit pupil to form a projected image. The waveguide may include a light coupling device (e.g., an input coupler, cross coupler and/or output coupler). However, light propagated through the waveguide may exhibit spatially-inhomogeneous power distribution within the coupled modes. This spatially-inhomogeneous power distribution may also lead to a non-uniform intensity profile at the light coupling device. Accordingly, this non-uniform intensity profile may broaden a point spread function associated with an output beam reflected towards the exit pupil thereby reducing a resolution of the projected image and resulting in non-uniform brightness of the projected image.